Add. $42+31+ 12+14=$
Explanation: First, let's add $42 + 31$. $$ $$ $$ $$ $$ ${+}$ $$ $$ $$ $$ ${=}$ $$ $$ $$ $$ $$ $$ $$ $$ $42} + {31} = 73$ Now, let's add $73$ to $12$. $$ $$ $$ $$ $$ $$ $$ $$ ${+}$ $$ $$ ${=}$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $73+ {12} =85$ Last, let's add $14$ to $85$. $$ $$ $$ $$ $$ $$ $$ $$ $$ ${+}$ $$ $$ ${=}$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $85+ {14} = 99$ $42+31+ 12+14=99$